But what message, exactly, did the strikes send? Many of the attack’s proponents have argued that it will show Syrian President Bashar al-Assad that the United States will punish his government if it uses chemical weapons again, and that this will deter it from choosing to do so. In fact, the strike’s message was ambiguous—and so it is misguided to assume that the attack will shape Assad’s behavior.

Ammar Abdullah / REUTERS

A civil defense member breathing through an oxygen mask after the gas attack in Khan Shaykhun, Syria, April 2017.

MIXED MESSAGES

There are three main ways that Assad might have interpreted the U.S. strike. In the first scenario, Assad takes the attack as a signal that the United States is serious about its commitment to using additional force in response to chemical weapons attacks. If this is how Assad views the strike, then the Syrian president would probably keep his forces from using chemical weapons again out of fear of U.S. retaliation. From the point of view of the United States, this is the most optimistic scenario, and the one that offers the most bang for the buck: a shift in Assad’s behavior in exchange for only 59 Tomahawk missiles.

In the second scenario, Assad sees the strike as a signal that the United States doesn’t much care about his regime’s use of chemical weapons. In response to an act that governments